[0001] The present disclosure relates to a dust collection system that operates in response
to a detected current flow in a power cord of a power tool.
[0002] The background description provided here is for the purpose of generally presenting
the context of the disclosure. Work of the presently named inventors, to the extent
it is described in this background section, as well as aspects of the description
that may not otherwise qualify as prior art at the time of filing, are neither expressly
nor impliedly admitted as prior art against the present disclosure.
[0003] Working with a power tool, such as a sander or a grinder, often means being surrounded
by a mass of dust and debris dispersed into the air by operation of the power tool.
A user may desire to run a vacuum whenever he is operating the power tool. Presently
available dust collection systems require connecting the power tool to the vacuum
itself, which may increase the cost of the vacuum since the power handling requirements
of the vacuum would be based on power consumed by the vacuum as well as the power
tool. Inside the vacuum, the hot and neutral conductors supplying power to the power
tool would be separated, and a current transformer around one or the other allows
for current measurement. The vacuum turns on when current is sensed going to the power
tool.
[0004] Other available dust collection systems require the user to plug the power tool into
an AC line splitter, which has a female power plug for a power cord of the power tool,
a male power plug for connecting to the wall (or an extension cord), and a middle
section where the hot and neutral conductors are physically separated. A current transformer
may be built into the AC line splitter to measure the current through one of the conductors.
Alternatively, a snap around meter may be clamped around one of the separated conductors
to measure current.
[0005] DE 4139847 A1 discloses a powered apparatus according to the preamble of claim 1.
[0006] According to an aspect of the present invention, there is provided a powered apparatus
as defined by claim 1.
[0007] According to another aspect of the present invention, there is provided a method
as defined by claim 7.
[0008] A powered apparatus includes a loop structure, a detection circuit, and a control
circuit. The loop structure includes an electromagnetic element and removably receives
a cord supplying power to a second powered apparatus. The electromagnetic element
senses current flow in the cord. The detection circuit generates a detection signal
in response to the current flow exceeding a threshold value. The control circuit selectively
turns on a motor of the powered apparatus in response to the generation of the detection
signal.
[0009] A dust collection system includes a sensor body, a selection circuit, a detection
circuit, and a motor control circuit. The sensor body detachably encircles a cord
supplying power to a power tool. The cord includes a neutral conductor and a hot conductor.
The sensor body houses sensors that, in response to current flow through the cord,
generate sensor signals. The selection circuit generates a positive output signal
in response to the sensor signals and generates a negative output signal in response
to the sensor signals. The detection circuit generates a current detection signal
in response to a comparison of the positive and negative output signals with a threshold.
The motor control circuit selectively turns on a motor of the dust collection system
in response to the current detection signal.
[0010] A method of operating a dust collection system includes attaching a sensor body around
a cord supplying power to a power tool. The cord includes a neutral conductor and
a hot conductor. The sensor body houses a plurality of sensors that, in response to
current flow through the cord, generate a plurality of sensor signals. The method
further includes generating a first output signal in response to the plurality of
sensor signals, and generating a second output signal in response to the plurality
of sensor signals. The method also includes generating a current detection signal
in response to comparing the first and second output signals to a threshold, and selectively
turning on a motor of the dust collection system in response to receiving the current
detection signal.
[0011] Further areas of applicability of the present disclosure will become apparent from
the detailed description, the claims and the drawings. The detailed description and
specific examples are intended for purposes of illustration only and are not intended
to limit the scope of the disclosure.
[0012] The present disclosure will become more fully understood from the detailed description
and the accompanying drawings, wherein:
FIGs. 1A and 1B are high-level functional block diagrams of example implementations
of a dust collection system;
FIGs. 2A-2C are functional block diagrams of example implementations of the dust collection
system;
FIG. 3A is a functional block diagram of a conditioning circuit of a clamp current
sensor;
FIG. 3B is a functional block diagram of a selection circuit of the clamp current
sensor;
FIG. 4A is a functional schematic of a conditioning circuit of the clamp current sensor;
FIG. 4B is a functional schematic of a selection circuit of the clamp current sensor;
FIG. 5 is a schematic diagram of a selection circuit redrawn for purposes of illustration;
FIG. 6A is a functional illustration of a top view of an example clamp current sensor
including axial inductor coils;
FIG. 6B is a functional illustration of a top view of another example clamp current
sensor in which circuit boards are arranged normal to the pivot plane of the clamp
current sensor;
FIG. 6C is a functional illustration of a top view of another example clamp current
sensor in which inductor coils are displaced axially;
FIGs. 6D and 6E are functional illustrations of an example clamp current sensor surrounding
a two-conductor power cord;
FIG. 6F is a functional illustration of an alternative physical implementation of
a clamp current sensor;
FIG. 6G is a graphical representation of an example curved inductor coil;
FIG. 7A is a flowchart illustrating a process for enabling a dust collector motor
in response to a current detection signal generation;
FIG. 7B is a flowchart illustrating a process executed by a processor that is powered
when a dust collector switch is not in an off state; and
FIG. 7C is a flowchart illustrating a process performed by a user in order to automatically
actuate a dust collector while operating a power tool.
[0013] In the drawings, reference numbers may be reused to identify similar and/or identical
elements.
[0014] Presently available dust collection systems capable of detecting current flow into
a power tool require a user to disconnect the power tool from the source of power
and connect the power tool to a special-purpose socket. The special-purpose socket
may be built into the housing of the dust collector or may be attached to the dust
collector. The power cord of a standard power tool contains two power-carrying conductors,
whose magnetic fields cancel each other out. A traditional snap around meter would
measure approximately zero current if snapped around both conductors at once. The
special-purpose socket separates the two conductors from each other and allows a current
measurement (such as with a current transformer) to be made around a single one of
the separated conductors.
[0015] The special-purpose socket adds cost to the dust collection system, creates inconvenience
for the user, and may limit the amount of current that can be drawn by the power tool.
According to the present disclosure, a dust collection system uses a clamp sensor
that snaps around the cord of the power tool to measure current, without the need
for a special-purpose socket. The clamp sensor can be snapped around the cord of the
power tool or around an extension cord (to which the power tool is connected) at any
position along the length of the cord or extension cord.
[0016] The power tool may be plugged into a separate electrical outlet from the dust collector,
and may even be on a different branch circuit. The separate electrical outlet may
be more conveniently located for plugging in the power tool than an outlet located
on a dust collector or a second outlet of a duplex receptacle into which the dust
collector is plugged. The branch circuit used for the power tool may have a higher
current handling capacity (e.g., 20 Amperes) than the branch circuit used for the
dust collector (e.g., 15 Amperes).
[0017] Although described in the context of a dust collection system, the present disclosure
is not so limited. The current sensing and operating aspects of this disclosure can
be applied to other electrical devices that may be enabled based on operation of another
device. For example only, a lubricant pump may be enabled based on operation of a
milling machine or drill press (where the lubricant may be oil) or based on operation
of a tile saw (where the lubricant may be water). In addition, the current sensing
and responsive operating may be applied to adjust operating parameters of an electrical
device. For example, an electrical generator may recognize a need to increase engine
torque or engine speed to satisfy an increased current demand (and prevent or mitigate
voltage sag) from a device consuming electrical power produced by the electrical generator.
[0018] In FIG. 1A, a dust collection system 100 includes a dust collector 104 that connects
to an AC outlet with a dust collector power cord 108. A power tool 112 is connected
to a second AC outlet via a power cord 116 attached to the power tool 112, which in
some cases is connected to the second AC outlet via an extension cord (not shown).
The dust collector 104 interfaces via a wired connection 120 with a clamp sensor 124.
In various implementations, the connection may be wireless, with the clamp sensor
124 powered by batteries or by power gleaned from the power cord 116. The clamp sensor
124 informs the dust collector 104 of current flowing to the power tool 112, which
allows the dust collector 104 to be actuated when the power tool 112 is turned on.
[0019] The clamp sensor 124 wraps (or, snaps) around the power cord 116 at any point along
the length of the power cord 116 or, when an extension cord is attached, at any point
along the length of the power cord 116 or the extension cord. The clamp sensor 124
may have a spring-loaded pivot that allows a user to open jaws of the clamp sensor
124, insert the power cord 116 into the open jaws, and release the jaws of the clamp
sensor 124 to secure the clamp sensor 124 around the power cord 116. In various implementations,
the clamp sensor 124 may apply enough pressure to the power cord 116 for friction
to prevent the clamp sensor 124 from freely sliding along the length of the power
cord 116.
[0020] In FIG. 1B, another example implementation of a dust collection system 150 is presented.
The clamp sensor 124 may be mounted directly to the housing of the dust collector
104 or be formed integrally with the housing. In an example implementation of the
clamp sensor 124 shown in FIG. 1B, a stationary member 154 is attached to the dust
collector, while a second member 158 is attached to the stationary member 154 by a
pivot 162. The power cord 116, which supplies power to the power tool 112, is passed
through the clamp sensor 124.
[0021] In various implementations, to save cost and/or to eliminate moving parts that may
pose an increased risk of failure, the clamp sensor 124 may instead be implemented
without the pivot 162, resulting in the stationary member 154 and the second member
158 being implemented as a single fixed body defining an opening for the power cord
116. In such a case, the power cord 116 would be fed through the clamp sensor 124.
As a result, the opening defined in the clamp sensor 124 would be designed to be large
enough for a standard power plug to fit through.
[0022] In FIG. 2A, an example implementation of the clamp sensor 124 includes sensors 200-1,
200-2, 200-3, 200-4 (collectively, sensors 200). Although four sensors are shown,
the present disclosure may include three or more sensors. Various implementations
may allow for two sensors to be used if an orientation of conductors in the power
cord is controlled with respect to positions of the two sensors. The sensors 200 may
be inductor coils radially positioned around the power cord 116 to detect the current
flow through conductors of the power cord 116. The sensors 200 each generate a separate
sensor signal in response to the current flow through the power cord 116. Each of
the sensors 200 may be located more closely to a specific one of the conductors of
the power cord 116 and therefore be more sensitive to the magnetic field of that conductor.
[0023] The sensors 200 provide the sensor signals to conditioning circuits 204-1, 204-2,
204-3, and 204-4 (collectively, conditioning circuits 204), respectively. The conditioning
circuits 204 create conditioned signals by amplifying the respective sensor signals
from the sensors 200. In various implementations, the conditioning circuits 204 also
apply various analog processing, such as low-pass, high-pass, or band-pass filtering.
[0024] A selection circuit 208 receives the conditioned signals from the conditioning circuits
204. Because positions of the sensors 200 with respect to conductors of the power
cord 116 are not tightly controlled (that is, the clamp sensor 124 may wrap around
the power cord 116 at an arbitrary angle), the selection circuit 208 identifies which
of the sensors 200 are receiving the strongest signal.
[0025] Specifically, in FIG. 2A, the selection circuit 208 generates a positive output signal
by selecting a highest signal from among the conditioned signals, and generates a
negative output signal by selecting a lowest signal from among the conditioned signals.
A detection circuit 212 is connected to the selection circuit 208 and receives the
positive output signal and the negative output signal. The detection circuit 212 generates
a current detection signal in response to the positive and negative output signals.
Specifically, the detection circuit 212 generates the current detection signal in
response to a difference between the positive and negative output signals exceeding
a threshold value.
[0026] The detection circuit 212 stops generating the current detection signal in response
to the difference between the positive and negative output signals falling below the
threshold value. In various implementations, the current detection signal may be conveyed
in a binary signal over a conductor, where generating the current detection signal
is performed by setting the conductor to an active level (such as a voltage corresponding
to digital one). Meanwhile, stopping generating the current detection signal is performed
by setting the conductor to an inactive level (such as a voltage corresponding to
digital zero).
[0027] An example implementation of the dust collector 104 includes an enabling circuit
216, a dust collector switch 220, a motor control circuit 224, a dust collector motor
228, and a DC source 232. As indicated in FIG. 2A, the DC source 232 supplies DC power
to the clamp sensor 124, which powers, for example, the conditioning circuits 204,
the selection circuit 208, and the detection circuit 212. The DC source 232 may also
supply power to the enabling circuit 216 and/or the motor control circuit 224.
[0028] The dust collector switch 220 has an on state, an off state, and an auto state. The
enabling circuit 216 is connected to the detection circuit 212 of the clamp sensor
124 and controls whether the motor control circuit 224 will run the dust collector
motor 228. For example, the enabling circuit 216 may generate an enable signal to
command starting the dust collector motor 228 and stop generating the enable signal
to command stopping the dust collector motor 228. The motor control circuit 224, when
commanded to run the dust collector motor 228, may execute closed-loop or open-loop
control to run the dust collector motor 228 at a predetermined speed, torque, and/or
power.
[0029] When the dust collector switch 220 is in the off state, power may be removed from
the motor control circuit 224 and/or the enabling circuit 216, automatically causing
the dust collector motor 228 to stop. When the dust collector switch 220 is in the
on state, the enabling circuit 216 generates the enable signal to command the motor
control circuit 224 to run the dust collector motor 228.
[0030] When the dust collector switch 220 is in the auto state, the enabling circuit 216
generates the enable signal in response to the detection circuit 212 generating the
current detection signal, indicating that current is flowing through the power cord.
The enabling circuit 216 continues to generate the enable signal, while the dust collector
switch 220 is in the auto state, for a predetermined period of time after generation
of the current detection signal stops.
[0031] FIGs. 2B and 2C illustrate alternative example implementations of the clamp sensor
124. In FIG. 2B, a processor 236 receives the conditioned signals from the conditioning
circuits 204. The processor 236 includes a built-in analog-to-digital converter (ADC)
240 that converts the conditioned signals from analog to digital. The ADC 240 may
be multiplexed, converting each of the conditioned signals to digital in a repeating
loop. Alternatively, the ADC 240 may include multiple ADC circuits to separately and
simultaneously convert the conditioned signals to digital.
[0032] A selection module 244 of the processor 236 receives the digital signals and selects
a highest one of the digital signals as a positive output signal. The selection module
244 also selects a lowest one of the digital conditioned signals as a negative digital
output signal. A detection module 248 generates a current detection signal in response
to the difference between the positive and negative output signals exceeding a threshold
value. The detection module 248 stops generating the current detection signal in response
to the difference between the positive and negative digital output signals falling
below the threshold value.
[0033] In FIG. 2C, a processor 250 includes an ADC 252 with an analog gain (i.e., amplification)
stage. The conditioning circuits 204 may therefore be eliminated. For example only,
the ADC 252 may be implemented using a Cypress Semiconductor PSoC® (programmable system-on-chip).
In various implementations, the sensors 200 are not separately powered and the DC
source 232 provides power directly to the processor 250.
[0034] In FIG. 3A, an example implementation of one of the conditioning circuits 204 includes
a first amplifier 300 that amplifies a sensor signal from the sensor 200 and also
performs low-pass filtering to remove noise and glitches. A second amplifier 304 further
amplifies an output of the first amplifier 300. A voltage reference circuit 308 supplies
a floating reference voltage to the first and second amplifiers, as discussed in more
detail below.
[0035] In FIG. 3B, an example implementation of the selection circuit 208 includes selection
sub-circuits 312-1 and 312-2 (collectively, selection sub-circuits 312). First and
second inputs of the selection sub-circuit 312-1 receive first and second conditioned
signals, respectively. A first output of the selection sub-circuit 312-1 is connected
to a first node 316 and a second output of the selection sub-circuit 312-1 is connected
to a second node 320.
[0036] First and second inputs of the selection circuit 312-2 receive third and fourth conditioned
signals, respectively. A first output of the selection sub-circuit 312-2 is connected
to the first node 316 and a second output of the selection sub-circuit 312-2 is connected
to the second node 320. The selection circuit 208 outputs the highest one of the conditioned
signals from the first node 316 and outputs the lowest one of the conditioned signals
from the second node 320.
[0037] In FIG. 4A, an example implementation of one of the sensors 200 includes an inductor
400 and a resistor 404. Current flow through the power cord 116 induces a secondary
current flow through the inductor 400 and the resistor 404 converts the induced current
into a voltage. In an example implementation of one of the conditioning circuits 204,
the first amplifier 300 includes an op-amp (operational amplifier) 408, a capacitor
412, a resistor 416, and a resistor 420.
[0038] The op-amp 408 is arranged in a noninverting configuration, and the values of the
resistor 416 and the resistor 420 are chosen to provide a greater-than-unity gain,
such as approximately 34. At high frequencies, the capacitor 412 reduces the gain
of the first amplifier 300 toward unity, acting as a low-pass filter. Because the
voltage across the resistor 404 may be positive or negative, a midpoint voltage reference
(labeled as MID in FIG. 4A) is introduced as an AC ground. The single-ended op-amp
408 then swings between VCC and ground around the midpoint voltage reference.
[0039] The second amplifier 304 includes an op-amp 424 in a noninverting configuration.
A coupling capacitor 428 allows the op-amp 424 to receive the output of the op-amp
408 without connecting the different DC bias points of the output of the op-amp 408
and the input of the op-amp 424.
[0040] A resistor 432 allows DC current to flow into a noninverting input of the op-amp
424. Resistors 436 and 440 create the noninverting configuration of the second amplifier
304 and are chosen to give a gain of greater than unity, such as approximately 11.
The op-amp 424 amplifies the signal generated by the op-amp 408 to create the conditioned
signal.
[0041] An example implementation of the voltage reference circuit 308 includes a regulator
444, a capacitor 448, and resistors 452 and 454. The regulator 444 is implemented
as a Zener diode shunt regulator in FIG. 4A. Because the conditioning circuit 204
may be located at the far end of a fairly thin-gauge wire from a source of power,
a capacitor 458 may be connected between VCC and ground to act as a decoupling capacitor
and to prevent supply voltage sags in response to increased current demands.
[0042] In FIG. 4B, an example implementation of the selection sub-circuit 312 receives the
first and second conditioned signals. The selection sub-circuit 312 includes diodes
456, 460, 464, and 468 connected in a full-wave rectifier configuration. The diodes
456, 460, 464, and 468 may be implemented as Schottky diodes.
[0043] The diodes 456, 460 are connected to the first node 316 via an optional diode protection
resistor 472 and the diodes 464, 468 are connected to the second node 320 via an optional
diode protection resistor 472. The resistors 472 and 476 can accommodate a high voltage
drop, such as from static electricity, that might otherwise damage the diodes 456,
460, 464, or 468.
[0044] FIG. 5 is an example implementation of the selection circuit 208 drawn to graphically
illustrate operation. The selection sub-circuit 312-1 includes the diodes 456, 460,
464, 468. The selection sub-circuit 312-2 includes diodes 500, 504, 508, and 512.
Note that for purposes of illustration, each of the conditioned signals is shown in
two locations in FIG. 5.
[0045] Each of the diodes 456, 460, 500, and 504 has an associated voltage drop when positively
biased. For example only, if the associated voltage drop is 0.4 V, the voltage at
the first node 316 is no more than 0.4 V below the first conditioned signal because
of the diode 456. Additionally, the voltage at the first node 316 is no more than
0.4 V below the second conditioned signal because of the diode 460. Therefore, the
voltage at the first node 316 is no more than 0.4 V below the highest of the conditioned
signals.
[0046] Similarly, the diodes 464, 468, 508, and 512 reduce the voltage of the second node
320 to at most 0.4 V above the lowest of the conditioned signals. The detection circuit
212 therefore receives the highest of the conditioned signals and the lowest of the
conditioned signals, offset only by the diode voltage drop. Although subtracting the
negative input from the positive input may not yield an accurate current measurement,
the difference is sufficiently responsive to detect the difference between the presence
of current flow and the absence of current flow.
[0047] In FIGs. 6A-6F, example implementations of clamp sensors show the sensors 200 positioned
so that when the clamp sensor is closed, the sensors 200 are spaced circumferentially
around the power cord 116.
[0048] In FIG. 6A, a first clamp sensor jaw 604 and a second clamp sensor jaw 608 are connected
by a pivot 612, which may be biased into a closed position by a spring (not shown).
The clamp sensor jaws 604, 608 clamp around the power cord 116.
[0049] A sheath 610 of the power cord 116 surrounds a neutral conductor 616, a hot conductor
620, and a ground conductor 624. The first clamp sensor jaw 604 includes a first circuit
board and the second clamp sensor jaw 608 includes a second circuit board, and the
circuit boards are perpendicular to an axis of the power cord 116. The sensors 200
are implemented as inductive coils in FIGs. 6A-6F. Coils 614-1, 614-2 are positioned
on the first circuit board and connected to circuits 600-1, 600-2, respectively. Similarly,
coils 614-3, 614-4 are positioned on the second circuit board and connected to circuits
600-3, 600-4, respectively. The coils 614-1, 614-2, 614-3, and 614-4 (collectively,
coils 614) are shown with an axial orientation.
[0050] The circuits 600-1, 600-2, 600-3, and 600-4 (collectively, circuits 600) may include
conditioning circuits, and the circuit boards may also include the selection circuit
208 and the detection circuit 212 of FIG. 2A. In various implementations, the first
selection sub-circuit 312-1 may be located on the circuit board in the first clamp
sensor jaw 604 and the second selection sub-circuit 312-2 may be located on the circuit
board in the second clamp sensor jaw 608.
[0051] FIG. 6B illustrates coils 628-1, 628-2, 628-3, and 628-4, which are shown with a
radial orientation. In addition, first and second circuit boards 630-1 and 630-2 are
arranged parallel with the axis of the power cord 116.
[0052] In FIG. 6C, the coils 640-1 and 640-2 are spaced apart in an axial direction with
respect to the power cord 116 so that the coils 640-1 and 640-2 can be positioned
closer together. In various implementations, the sensor 640-1 is offset ninety degrees
from the sensor 640-2. Coils 640-3 and 640-4 are similarly positioned in the body
of the second clamp sensor jaw 608.
[0053] FIGs. 6D-6E illustrates a 2-conductor power cord 650 including a hot conductor 654
and a neutral conductor 658. Although FIGs. 6D and 6E depict only two orientations
of the power cord 650, positions of the coils 640 may be chosen so that any orientation
of the power cord 650 will allow for current detection. In various implementations,
the same clamp sensor may be used interchangeably with two-conductor or three-conductor
power cords.
[0054] FIG. 6F shows another example implementation of the clamp sensor. A pivoting arm
680 is attached to a body 684, which includes a circuit board. Some of the coils 614,
such as coils 614-1 and 614-2 are positioned on the body 684 while others of the coils
614, such as coils 614-3 and 614-4, are positioned on the pivoting arm 680.
[0055] In FIG. 6G, an alternative inductive coil 690 is shown, where the core is not cylindrical
but is instead C-shaped. The coil 690 can be used in place of some or all of the coils
614, 628, and 640.
[0056] In FIG. 7A, a process executed by the dust collection system 100 begins at 700. If
the dust collector switch 220 is in the on state, control transfers to 702; otherwise,
control transfers to 704. At 702, control causes the dust collector motor to run and
control returns to 700. At 704, control determines whether the dust collector switch
220 is in the off state. If so, control transfers to 706; otherwise, control transfers
to 708. At 706, control causes the dust collector motor to stop running and control
returns to 700.
[0057] At 708, control determines whether the dust collector switch is in the auto state.
If so, control transfers to 712; otherwise, control returns to 700. At 712, control
conditions sensor signals, determines a highest one of the conditioned sensor signals,
and determines a lowest one of the conditioned sensor signals. Control then determines
the difference between the highest signal and lowest signal.
[0058] At 716, control compares the difference to a threshold value. In response to the
difference exceeding the threshold value, meaning that current has been detected in
the power cord, control transfers to 720; otherwise, control transfers to 722. At
720, control resets an Off_Timer, which tracks the amount of time since current has
not been detected in the power cord. At 724, control causes the dust collector motor
to run and returns to 700.
[0059] At 722, current is no longer detected, so if the Off_Timer is greater than a time
delay, control transfers to 732, where control causes the dust collector motor to
stop (or remain stopped). Control then returns to 700. The time delay controls how
long the dust collector motor should remain running after the power tool has shut
off. The time delay also prevents spurious shut-offs that may occur if control temporarily
fails to detect current in the power cord. If, at 722, the Off_Timer is not yet greater
than the time delay, control simply returns to 700.
[0060] FIG. 7B is similar to FIG. 7A, with 704 and 706 being omitted. In various implementations,
a processor executing the control shown in FIG. 7B will not receive power and will
therefore be off when the dust collector switch 220 is in the off state. As a result,
the processor will never reach 706 of FIG. 7A, because once the dust collector switch
220 is in the off state, operation of the processor will stop.
[0061] In FIG. 7C, a user begins automatic dust collection operation at 750 by plugging
the dust collector into a first receptacle. At 754, the user plugs the power tool
into a second receptacle. At 758, the user passes the cord of the power tool through
the clamp sensor. For example, this may involve opening a jaw or moving member of
the power tool, placing the cord in the opening of the clamp sensor, and closing (or
allowing to close) the moving member. In implementations where the clamp sensor has
no moving parts, the cord may be passed through the clamp sensor prior to plugging
the power tool into the second receptacle. At 762, the user sets a switch on the dust
collector to an auto position.
[0062] At 766, when the user begins operating the power tool, control transfers to 770;
otherwise, control remains at 766. At 770, the dust collector runs in response to
sensing that current is being provided to the power tool. At 774, if operation of
the power tool has stopped, control transfers to 778; otherwise, control remains at
774. At 778, the dust collector stops running in response to sensing that current
is no longer being provided to the power tool. In various implementations, the dust
collector may stop running after a predetermined delay following the operation of
the power tool having stopped. Control then returns to 766.
[0063] The foregoing description is merely illustrative in nature and is in no way intended
to limit the disclosure, its application, or uses. The broad teachings of the disclosure
can be implemented in a variety of forms. Therefore, while this disclosure includes
particular examples, the true scope of the disclosure should not be so limited since
other modifications will become apparent upon a study of the drawings, the specification,
and the following claims. As used herein, the phrase at least one of A, B, and C should
be construed to mean a logical (A or B or C), using a non-exclusive logical OR. It
should be understood that one or more steps within a method may be executed in different
order (or concurrently) without altering the principles of the present disclosure.
[0064] In this application, including the definitions below, the term module may be replaced
with the term circuit. The term module may refer to, be part of, or include an Application
Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete
circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational
logic circuit; a field programmable gate array (FPGA); a processor (shared, dedicated,
or group) that executes code; memory (shared, dedicated, or group) that stores code
executed by a processor; other suitable hardware components that provide the described
functionality; or a combination of some or all of the above, such as in a system-on-chip.
[0065] The term code, as used above, may include software, firmware, and/or microcode, and
may refer to programs, routines, functions, classes, and/or objects. The term shared
processor encompasses a single processor that executes some or all code from multiple
modules. The term group processor encompasses a processor that, in combination with
additional processors, executes some or all code from one or more modules. The term
shared memory encompasses a single memory that stores some or all code from multiple
modules. The term group memory encompasses a memory that, in combination with additional
memories, stores some or all code from one or more modules. The term memory may be
a subset of the term computer-readable medium. The term computer-readable medium does
not encompass transitory electrical and electromagnetic signals propagating through
a medium, and may therefore be considered tangible and non-transitory. Non-limiting
examples of a non-transitory tangible computer readable medium include nonvolatile
memory, volatile memory, magnetic storage, and optical storage.
[0066] The apparatuses and methods described in this application may be partially or fully
implemented by one or more computer programs executed by one or more processors. The
computer programs include processor-executable instructions that are stored on at
least one non-transitory tangible computer readable medium. The computer programs
may also include and/or rely on stored data.
1. A dust collecting system (100) comprising:
a dust collector (104) and a dust collector motor (228),
a clamp sensor (124) detachably encircling a cord (116) supplying power to a power
tool (112), wherein the cord (112) includes a neutral conductor and a hot conductor,
characterized in that:
the clamp body houses a plurality of sensors (200) that, in response to current flow
through the cord (116), generate a plurality of sensor signals;
the sensor signals being provided to conditioning circuits (204) which create conditioned
signals,
the system further comprising a selection circuit (208) that generates a positive
output signal by selecting a highest signal from among the conditioned signals and
generates a negative output signal by selecting a lowest signal from among the conditioned
signals;
a detection circuit (212) connected to the selection circuit (208) that generates
a current detection signal in response to a difference between the positive and negative
output signals exceeding a threshold value; and
a motor control circuit (224) that selectively turns on the dust collector motor (228)
of the dust collecting system (100) apparatus in response to the current detection
signal.
2. The dust collection system (100) of claim 1 wherein the detection circuit (212) stops
generating the current detection signal in response to the difference between the
positive and negative output signals falling below the threshold value.
3. The dust collection system (100) of claim 1 wherein the selection circuit (208) generates
the positive output signal by selecting a highest signal based on the plurality of
sensor signals and generates the negative output signal by selecting a lowest signal
based on the plurality of sensor signals.
4. The dust collection system (100) of claim 1 wherein the plurality of sensor signals
are amplified to create a plurality of conditioned signals, respectively, and wherein
the selection circuit (208) generates the positive and negative output signals in
response to the plurality of conditioned signals.
5. The dust collection system (100) of claim 1 wherein each of the plurality of sensors
comprises an inductive coil.
6. The dust collection system (100) of claim 1 wherein:
the plurality of sensors (200) comprises at least four sensors (200-1, 200-2, 200-3,
200-4),
the selection circuit (208) includes a first full-wave rectifier and a second full-wave
rectifier,
first and second inputs of the first full-wave rectifier receive signals based on
first and second sensors (200-1, 200-2) of the plurality of sensors (200), respectively,
a first output of the first full-wave rectifier is connected to a first node (316),
a second output of the first full-wave rectifier is connected to a second node (320),
first and second inputs of the second full-wave rectifier receive signals based on
third and fourth sensors (200-3, 200-4) of the plurality of sensors (200), respectively,
a first output of the second full-wave rectifier is connected to the first node (316),
a second output of the second full-wave rectifier is connected to the second node
(320),
a voltage of the first node (316) is output from the selection circuit (208) as the
positive output signal, and
a voltage of the second node (320) is output from the selection circuit (208) as the
negative output signal.
7. A method of operating a dust collection system (100) comprising a dust collector (104)
and a dust collector motor (228), the method comprising:
attaching a clamp sensor (124) around a cord (116) supplying power to a power tool
(112), the cord (116) including a neutral conductor and a hot conductor, characterised by the clamp sensor (124) housing a plurality of sensors (200) that, in response to
current flow through the cord (116), generate a plurality of sensor signals; the sensor
signals being provided to conditioning circuits (204) which create conditioned signals,
generating a positive output signal by selecting a highest signal among the conditioned
signals;
generating a negative output signal by selecting a lowest signal from among the conditioned
signals,
generating a current detection signal in response to a difference between the positive
and negative output signals exceeding a threshold value; and
selectively turning on the dust collector motor (228) of the dust collection system
in response to receiving the current detection signal.
8. The method of claim 7 wherein a switch (220) of the dust collection system has an
on position, an off position, and an auto position, and wherein the method further
comprises turning on the motor (228), while the switch (220) is in the auto position,
in response to generation of the current detection signal.
9. The method of claim 8 further comprising turning on the motor (228) irrespective of
the current detection signal while the switch (220) is in the on position.
10. The method of claim 8 further comprising, while the switch (220) is in the auto position,
turning off the motor (228) after a predetermined delay subsequent to generation of
the current detection signal being stopped.
11. The method of claim 7, further comprising:
generating a first output signal in response to the plurality of sensor signals; and
generating a second output signal in response to the plurality of sensor signals,
wherein the generating the current detection signal is performed in response to a
difference between the first and second output signals exceeding the lower threshold
value.
12. The method of claim 11 further comprising:
amplifying the plurality of sensor signals to create a plurality of conditioned signals,
respectively;
selecting a highest one of the plurality of conditioned signals as the first output
signal; and
selecting a lowest one of the plurality of conditioned signals as the second output
signal.
1. Staubsammelsystem (100), umfassend:
einen Staubsammler (104) und einen Staubsammlermotor (228),
einen Klemmensensor (124), der abnehmbar ein Kabel (116) umgibt, das ein Elektrowerkzeug
(112) mit Strom versorgt, wobei das Kabel (112) einen Neutralleiter und einen Phasenleiter
umfasst, dadurch gekennzeichnet, dass:
der Klemmkörper eine Vielzahl von Sensoren (200) aufnimmt, die als Reaktion auf Stromfluss
durch das Kabel (116) eine Vielzahl von Sensorsignalen erzeugt;
die Sensorsignale Konditionierungsschaltungen (204) bereitgestellt werden, die konditionierte
Signale erzeugen,
wobei das System weiter eine Auswahlschaltung (208) umfasst, die ein positives Ausgangssignal
durch Auswählen eines höchsten Signals aus den konditionierten Signalen erzeugt und
ein negatives Ausgangssignal durch Auswählen eines niedrigsten Signals aus den konditionierten
Signalen erzeugt;
eine Erfassungsschaltung (212), die mit der Auswahlschaltung (208) verbunden ist,
die ein Stromerfassungssignal als Reaktion auf eine Differenz zwischen den positiven
und den negativen Ausgangssignalen erzeugt, die einen Schwellenwert überschreiten;
und
eine Motorsteuerschaltung (224), die den Staubsammlermotor (228) der Staubsammelsystemeinrichtung
(100) als Reaktion auf das Stromerfassungssignal selektiv einschaltet.
2. Staubsammelsystem (100) nach Anspruch 1, wobei die Erfassungsschaltung (212) aufhört,
das Stromerfassungssignal als Reaktion auf die Differenz zwischen den positiven und
negativen Ausgangssignalen zu erzeugen, die unterhalb des Schwellenwerts fallen.
3. Staubsammelsystem (100) nach Anspruch 1, wobei die Auswahlschaltung (208) das positive
Ausgangssignal durch Auswählen eines höchsten Signals basierend auf der Vielzahl von
Sensorsignalen erzeugt und das negative Ausgangssignal durch Auswählen eines niedrigsten
Signals basierend auf der Vielzahl von Sensorsignalen erzeugt.
4. Staubsammelsystem (100) nach Anspruch 1, wobei die Vielzahl von Sensorsignalen verstärkt
wird, um eine Vielzahl von konditionierten Signalen zu erzeugen, und wobei die Auswahlschaltung
(208) die positiven und negativen Ausgangssignale als Reaktion auf die Vielzahl von
konditionierten Signalen erzeugt.
5. Staubsammelsystem (100) nach Anspruch 1, wobei jeder der Vielzahl von Sensoren eine
Induktionsspule umfasst.
6. Staubsammelsystem (100) nach Anspruch 1, wobei:
die Vielzahl von Sensoren (200) mindestens vier Sensoren (200-1, 200-2, 200-3, 200-4)
umfasst,
die Auswahlschaltung (208) einen ersten Vollweggleichrichter und einen zweiten Vollweggleichrichter
einschließt,
erste und zweite Eingänge des ersten Vollweggleichrichters Signale basierend auf dem
ersten bzw. dem zweiten Sensor (200-1, 200-2) der Vielzahl von Sensoren (200) empfangen,
ein erster Ausgang des ersten Vollweggleichrichters mit einem ersten Knoten (316)
verbunden ist,
ein zweiter Ausgang des ersten Vollweggleichrichters mit einem zweiten Knoten (320)
verbunden ist,
erste und zweite Eingänge des zweiten Vollweggleichrichters Signale basierend auf
dem dritten bzw. dem vierten Sensor (200-3, 200-4) der Vielzahl von Sensoren (200)
empfangen,
ein erster Ausgang des zweiten Vollweggleichrichters mit dem ersten Knoten (316) verbunden
ist,
ein zweiter Ausgang des zweiten Vollweggleichrichters mit dem zweiten Knoten (320)
verbunden ist,
eine Spannung des ersten Knotens (316) von der Auswahlschaltung (208) als positives
Ausgangssignal ausgegeben wird, und
eine Spannung des zweiten Knotens (320) von der Auswahlschaltung (208) als negatives
Ausgangssignal ausgegeben wird.
7. Verfahren zum Betreiben eines Staubsammelsystems (100), umfassend einen Staubsammler
(104) und einen Staubsammlermotor (228), wobei das Verfahren umfasst:
Anbringen eines Klemmensensors (124) um ein Kabel (116), das ein Elektrowerkzeug (112)
mit Strom versorgt, wobei das Kabel (116) einen Neutralleiter und einen Phasenleiter
einschließt, gekennzeichnet durch den Klemmensensor (124), der eine Vielzahl von Sensoren (200) aufnimmt, die als Reaktion
auf Stromfluss durch das Kabel (116) eine Vielzahl von Sensorsignalen erzeugt;
die Sensorsignale Konditionierungsschaltungen (204) bereitgestellt werden, die konditionierte
Signale erzeugen,
Erzeugen eines positiven Ausgangssignals durch Auswählen eines höchsten Signals unter
den konditionierten Signalen;
Erzeugen eines negativen Ausgangssignals durch Auswählen eines niedrigsten Signals
aus den konditionierten Signalen,
Erzeugen eines Stromerfassungssignals als Reaktion auf eine Differenz zwischen den
positiven und den negativen Ausgangssignalen, die einen Schwellenwert überschreiten;
und
selektives Einschalten des Staubsammlermotors (228) des Staubsammelsystems als Reaktion
auf den Empfang des Stromerfassungssignals.
8. Verfahren nach Anspruch 7, wobei ein Schalter (220) des Staubsammelsystems eine Ein-Position,
eine Aus-Position und eine Auto-Position aufweist und wobei das Verfahren weiter das
Einschalten des Motors (228) umfasst, während sich der Schalter (220) in der Auto-Position
als Reaktion auf die Erzeugung des Stromerfassungssignals befindet.
9. Verfahren nach Anspruch 8, weiter umfassend das Einschalten des Motors (228) unabhängig
von dem Stromerfassungssignal, während sich der Schalter (220) in der Ein-Position
befindet.
10. Verfahren nach Anspruch 8, weiter umfassend, während sich der Schalter (220) in der
Auto-Position befindet, Ausschalten des Motors (228) nach einer vorbestimmten Verzögerung
nach der Erzeugung des Stromerfassungssignals, das angehalten wird.
11. Verfahren nach Anspruch 7, weiter umfassend:
Erzeugen eines ersten Ausgangssignals als Reaktion auf die Vielzahl von Sensorsignalen;
und
Erzeugen eines zweiten Ausgangssignals als Reaktion auf die Vielzahl von Sensorsignalen,
wobei das Erzeugen des Stromerfassungssignals als Reaktion auf eine Differenz zwischen
dem ersten und dem zweiten Ausgangssignal durchgeführt wird, die den unteren Schwellenwert
überschreiten.
12. Verfahren nach Anspruch 11, weiter umfassend:
Verstärken der Vielzahl von Sensorsignalen, um jeweils eine Vielzahl von konditionierten
Signale zu erzeugen;
Auswählen eines höchsten aus der Vielzahl von konditionierten Signalen als das erste
Ausgangssignal; und
Auswählen eines niedrigsten aus der Vielzahl von konditionierten Signalen als zweites
Ausgangssignal.
1. Système de collecte de poussière (100), comprenant :
un collecteur de poussière (104) et un moteur de collecteur de poussière (228),
un capteur de serrage (124) encerclant de manière amovible un cordon (116) alimentant
un outil électrique (112), dans lequel
le cordon (112) inclut un conducteur neutre et un conducteur chaud, caractérisé en ce que :
le corps de serrage loge une pluralité de capteurs (200) qui, en réponse à un flux
de courant à travers le cordon (116), génèrent une pluralité de signaux de capteur
;
les signaux de capteur étant fournis à des circuits de conditionnement (204) qui créent
des signaux conditionnés,
le système comprenant en outre un circuit de sélection (208) qui génère un signal
de sortie positif en sélectionnant un signal le plus élevé parmi les signaux conditionnés
et génère un signal de sortie négatif en sélectionnant un signal le plus bas parmi
les signaux conditionnés ;
un circuit de détection (212) connecté au circuit de sélection (208) qui génère un
signal de détection de courant en réponse à une différence entre les signaux de sortie
positif et négatif dépassant une valeur de seuil ; et
un circuit de commande de moteur (224) qui met sélectivement en marche le moteur de
collecteur de poussière (228) de l'appareil du système collecteur de poussière (100)
en réponse au signal de détection de courant.
2. Système de collecte de poussière (100) selon la revendication 1, dans lequel le circuit
de détection (212) arrête de générer le signal de détection de courant en réponse
à la différence entre les signaux de sortie positif et négatif tombant en dessous
de la valeur de seuil.
3. Système de collecte de poussière (100) selon la revendication 1, dans lequel le circuit
de sélection (208) génère le signal de sortie positif en sélectionnant un signal le
plus élevé sur la base de la pluralité de signaux de capteur et génère le signal de
sortie négatif en sélectionnant un signal le plus bas sur la base de la pluralité
de signaux de capteur.
4. Système de collecte de poussière (100) selon la revendication 1, dans lequel la pluralité
de signaux de capteur sont amplifiés pour créer une pluralité de signaux conditionnés,
respectivement, et dans lequel le circuit de sélection (208) génère les signaux de
sortie positif et négatif en réponse à la pluralité de signaux conditionnés.
5. Système de collecte de poussière (100) selon la revendication 1, dans lequel chacun
de la pluralité de capteurs comprend une bobine inductive.
6. Système de collecte de poussière (100) selon la revendication 1 dans lequel :
la pluralité de capteurs (200) comprend au moins quatre capteurs (200-1, 200-2, 200-3,
200-4),
le circuit de sélection (208) inclut un premier redresseur pleine onde et un second
redresseur pleine onde,
des première et seconde entrées du premier redresseur pleine onde reçoivent des signaux
basés sur des premier et deuxième capteurs (200-1, 200-2) de la pluralité de capteurs
(200), respectivement,
une première sortie du premier redresseur pleine onde est connectée à un premier nœud
(316),
une seconde sortie du premier redresseur pleine onde est connectée à un second noeud
(320),
des première et seconde entrées du second redresseur pleine onde reçoivent des signaux
basés sur des troisième et quatrième capteurs (200-3, 200-4) de la pluralité de capteurs
(200), respectivement,
une première sortie du second redresseur pleine onde est connectée au premier nœud
(316),
une seconde sortie du second redresseur pleine onde est connectée au second noeud
(320),
une tension du premier nœud (316) est délivrée en sortie à partir du circuit de sélection
(208) en tant que signal de sortie positif, et
une tension du second nœud (320) est délivrée en sortie à partir du circuit de sélection
(208) en tant que signal de sortie négatif.
7. Procédé de fonctionnement d'un système de collecte de poussière (100) comprenant un
collecteur de poussière (104) et un moteur de collecteur de poussière (228), le procédé
comprenant les étapes consistant à :
fixer un capteur de serrage (124) autour d'un cordon (116) alimentant un outil électrique
(112), le cordon (116) incluant un conducteur neutre et un conducteur chaud, caractérisé en ce que le capteur de serrage (124) loge une pluralité de capteurs (200) qui, en réponse
à un flux de courant à travers le cordon (116), génèrent une pluralité de signaux
de capteur; les signaux de capteur étant fournis à des circuits de conditionnement
(204) qui créent des signaux conditionnés,
générer un signal de sortie positif en sélectionnant un signal le plus élevé parmi
les signaux conditionnés ;
générer un signal de sortie négatif en sélectionnant un signal le plus bas parmi les
signaux conditionnés,
générer un signal de détection de courant en réponse à une différence entre les signaux
de sortie positif et négatif dépassant une valeur de seuil ; et
mettre sélectivement en marche le moteur de collecteur de poussière (228) du système
de collecte de poussière en réponse à la réception du signal de détection de courant.
8. Procédé selon la revendication 7, dans lequel un commutateur (220) du système de collecte
de poussière présente une position de marche, une position d'arrêt et une position
automatique, et dans lequel le procédé comprend en outre une mise en marche du moteur
(228), tandis que le commutateur (220) est dans la position automatique, en réponse
à la génération du signal de détection de courant.
9. Procédé selon la revendication 8, comprenant en outre une mise en marche du moteur
(228) indépendamment du signal de détection de courant pendant que le commutateur
(220) est dans la position de marche.
10. Procédé selon la revendication 8, comprenant en outre, pendant que le commutateur
(220) est dans la position automatique, un arrêt du moteur (228) après un retard prédéterminé
après que la génération du signal de détection de courant soit stoppée.
11. Procédé selon la revendication 7, comprenant en outre les étapes consistant à :
générer un premier signal de sortie en réponse à la pluralité de signaux de capteur
; et
générer un second signal de sortie en réponse à la pluralité de signaux de capteur,
dans lequel la génération du signal de détection de courant est effectuée en réponse
à une différence entre les premier et second signaux de sortie dépassant la valeur
de seuil inférieure.
12. Procédé selon la revendication 11 comprenant en outre les étapes consistant à :
amplifier la pluralité de signaux de capteur pour créer une pluralité de signaux conditionnés,
respectivement;
sélectionner un le plus élevé de la pluralité de signaux conditionnés en tant que
premier signal de sortie ; et
sélectionner un le plus bas de la pluralité de signaux conditionnés en tant que second
signal de sortie.